1. Field of the Invention
The present invention relates to snowmobile chassis or frame construction.
2. Prior Art
In the prior art, it has been common to provide heavy structural members which extend from the front of the tunnel that normally houses the drive track for the snowmobile forwardly to carry the hubs for the ski spindles used for steering the snowmobile and to support the engine. Placing large structural elements immediately ahead of the tunnel results in raising the engine of the snowmobile to clear the structural elements so that the center of gravity of the snowmobile is unnecessarily raised. The basic problem has been in getting enough rigidity in the entire frame of the machine to prevent racking and twisting (torsional weakness) of the snowmobile chassis.
U.S. Pat. No. 3,548,961 shows means for attempting to strengthen the tunnel of a snowmobile for obtaining torsional rigidity and lowering the stress in some of the frame members to prevent failure of the frame.
However, again, the structure at the front portions of the tunnel is conventional in this patent.
U.S. Pat. No. 3,709,312 also shows a snowmobile construction which has a front pan or housing for an engine, but does not disclose the means for supporting the skis with respect to the chassis of the snowmobile. At first glance, the structure of U.S. Pat. No. 3,709,312 would resemble the present device, but no means for structurally reinforcing the perimeter members is in U.S. Pat. No. 3,709,212 and there is no suggestion that such structural rigidity is a problem. It is believed that the showing is merely schematic in U.S. Pat. No. 3,709,312.
It has been known to extend front ski supports directly from the side walls of the tunnel, and to use side panels such as those in U.S. Pat. No. 3,871,460 but again this is a narrow spacing without adequate room for nesting an engine in between the structural members for the ski supports. In U.S. Pat. No. 3,871,460 drive shafts and the like must extend through front frame panels to achieve lowering of the engine.